Clinical Significance of Degree of Iliocaval Obstruction Based on Intravascular Ultrasound Use

Abstract Objective: Endovenous therapy serves as the preferred treatment for patients with May–Thurner syndrome (MTS) who have significant symptoms. While stenting for MTS generally yields better results than for postthrombotic syndrome, it remains unclear whether the severity of stenosis specifically in MTS influences these outcomes. This study aims at assessing the effect of the degree of stenosis on endovascular therapy for MTS. Methods: The retrospective study included 73 patients who presented for deep venous stenting of the lower limb at a tertiary center between 2018 and 2022. Based on the intravascular ultrasound (IVUS) use, patients were divided into two groups according to degree of stenosis: 50%–80% and >80% stenosis. Both groups were compared regarding demographics, clinical presentations, procedural details, and postoperative outcomes. Results: Significant > 80% stenosis was detected in 45.2% of cases. There was no significant difference regarding demographics and comorbidities except for body mass index (BMI) as patients with >80% stenosis were more likely to have higher BMI ( P = 0.05). Patients with >80% stenosis were more likely to have a prior history of DVT (21.2% vs. 5%; P = 0.036). There was no statistical difference in the clinical picture of both groups except for higher rates of active venous ulcer in patients with >80% stenosis (21% vs. 5%: P =0.001). Patients with 50%–80% stenosis were more likely to present with atypical varicosities (50% vs. 21%; P = 0.011). Patients with >80% stenosis were more likely to have venographic features of stenosis as pelvic collateral and ascending lumbar veins ( P = 0.0007 and P < 0.0001, respectively). After a mean clinical follow-up of 414.6 ± 587.5, primary patency was higher for the 50%–80% stenosis, 90.9% versus 74.4% (Log-rank test = 0.012). Conclusion: The severity of iliac vein stenosis/compression is associated with more advanced clinical presentations and more venographic signs of collateralizations. IVUS serves as a more sensitive tool than computed tomography venography in detecting left common iliac vein critical stenosis. More than 80% can serve as a proper cutoff point for critical venous stenosis that warrants more aggressive therapy and closer follow-up. A critical degree of stenosis was associated with lower patency rates when compared to 50%–80% stenosis.